In this study, novel umami peptides were prepared from oyster (
) hydrolysates, and their umami mechanisms were investigated. Umami fractions G2 and G3 were isolated by gel filtration chromatography ...(GFC) and sensory evaluation. The umami scores of the G2 and G3 fractions were 7.8 ± 0.12 and 7.5 ± 0.18, respectively. 36 potential umami peptides with molecular weights below 1500 Da, E and D accounting for >30% of the peptides and iUmami-SCM > 588 were screened by peptidomics. Peptide source analysis revealed that myosin, paramyosin, and sarcoplasmic were the major precursor proteins for these peptides. The electronic tongue results demonstrated that the synthetic peptides DPNDPDMKY and NARIEELEEE possessed an umami characteristic, whereas SIEDVEESRNK and ISIEDVEESRNK possessed a saltiness characteristic. Additionally, molecular docking results indicated that the umami peptide (DPNDPDMKY, NARIEELEEE, SIEDVEESRNK, and ISIEDVEESRNK) binds to H145, S276, H388, T305, Y218, D216, and Q389 residues in the T1R3 taste receptor via a conventional hydrogen bond and a carbon-hydrogen bond. This research provides a new strategy for the screening of umami peptides.
Two water-soluble polysaccharides were extracted and purified from mung bean (Vigna radiate) skin by cellulose-enzyme assisted extraction (MBP-1) and hot-water extraction (MBP-2), respectively. The ...physicochemical properties, antioxidant and antibacterial activities of MBP-1 and MBP-2 were investigated and compared. Results showed that MBP-1 and MBP-2 had different sugar, protein, and uronic acid contents. MBP-1 was consisted of rhamnose (Rha), arabinose (Ara), galactose (Gal), glucose (Glc), xylose (Xyl), mannose (Man), and galacturonic acid (GalA), MBP-2 was mainly composed of Rha, Ara, Gal, Glc, Xyl, fructose (Fru), and GalA, and with molecular weights (Mws) of 139 and 208 kDa, respectively. Thermal gravimetric analysis (TGA) suggested that MBP-2 had more a stable structure than MBP-1. Antioxidant assay showed that they all exhibited strong DPPH•, •OH and ABTS+• radicals scavenging abilities. MBP-1 and MBP-2 also exhibited moderate antibacterial activities against both Gram-positive (G+) and Gram-negative (G−) bacteria.
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•Two mung bean skin polysaccharides were extracted by cellulose-enzyme assisted (MBP-1) and hot-water extraction (MBP-2).•MBP-1 and MBP-2 had strong radical scavenging ability.•MBP-1 and MBP-2 polysaccharides exhibited moderate antibacterial activities.
The effect of sulfated modification on the physicochemical properties and antioxidant activities of polysaccharide (MP) from Mesona chinensis Benth were investigated by chemical methods, Fourier ...transform infrared spectroscopy, high performance anion exchange chromatography, and establishing oxidative stress model and free radical model. Results showed that sulfated modification caused a significant change in chemical composition and the apparent structure of MP, but the degradation of the main chain of MP was inconspicuous. Sulfated Mesona chinensis Benth polysaccharide (SMP) exhibited excellent free radical scavenging activities and improved the protective effect of MP on cellular oxidative stress by increasing superoxide dismutase (SOD) activity and decreasing malondialdehyde (MDA) content. This study suggested that sulfated modification is an effective method to improve the antioxidant activities of MP, so as to expand the development and application of MP.
•Polysaccharide from the Mesona chinensis Benth was sulfated successfully.•The composition and surface morphology of the polysaccharide changed after sulfated.•Polysaccharide was sulfated to improve its antioxidant activity.•Polysaccharide was sulfated to reduce cellular oxidative stress.
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•Ultrafine grinding can change the flavor characteristics of fish gelatin.•65 volatile compounds were identified by HS-SPME-GC-MS.•46 volatile compounds were identified by ...HS-GC-IMS.•The microstructure of FG particles changed significantly.
Three different methods were used to identify and analyze the flavor of fish gelatin with different ultrafine grinding time (0, 2, 4 and 8 h). The results of electronic nose showed that overall flavor of the samples changed. HS-SPME-GC-MS identified 65 volatile compounds, including 18 aldehydes, 7 ketones, 7 alkanes, 11 alcohols, 8 esters, 7 phenols, and 7 acids. HS-GC-IMS identified 46 volatile compounds, including 21 aldehydes, 5 ketones, 5 alcohols, 6 esters, 7 acids, 1 ether, and 1 amine. The particle size analysis results indicate that the size distribution decreases from 918.97–1167.16 and 1388.81–1780.40 nm to 157.63–177.37 and 285.90–344.55 nm with the increased of grinding time. The SEM analysis results indicate that the change in flavor characteristics of FG is due to the different storage and release abilities of volatile compounds in FG with different particle sizes.
A method was developed for the determination of N-carbamyl-L-glutamic acid (NCG) in feedstuff by high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry ...(HPLC-ESI-MS/MS). The feedstuff samples were extracted with methanol, cleaned-up by a ProElut mixed-mode of strong anion exchange inverse column (PXA). Then the samples were separated with HPLC and detected with MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI+). The fragment ions of m/z 148.0 and m/z 84.0 were used for qualitative analysis, and m/z 130.0 was selected for quantitative analysis. The limit of detection for NCG was 24 microg/kg (S/N > 3), and the limit of quantification was 80 microg/kg (S/N > 10). The standard calibration curve was linear over the range of 20-1,000 microg/L, and the correlation coefficient was 0. 999 9. The recoveries of NCG in feedstuff were 104.0%, 103.5%, 95.3%, at the three spiked levels of 80, 200, 500 mg/kg with the relative standard de
•A newly developed continuous fast microwave-assisted pyrolysis system was used.•It is the first time to pyrolysis Camellia oleifera shell with microwave.•The effects of temperature and feed rate on ...pyrolysis were studied.
In this study, a continuous fast microwave-assisted pyrolysis system was developed to produce bio-oil, gas, and biochar from rice straw and Camellia oleifera shell. The effects of different pyrolysis temperatures (400 °C, 500 °C, and 600 °C) and feed rates (rice straw: 25, 45, and 66 g/min; C. oleifera shell: 100, 200, and 400 g/min) on bio-oil production were investigated. Experimental results showed that the yields of bio-oil (31.86 wt%) and gas (54.49 wt%) produced by the microwave-assisted pyrolysis of rice straw increased with increasing temperature. By contrast, the yields of bio-oil (27.45 wt%) and biochar (35.47 wt%) produced by the pyrolysis of C. oleifera shell decreased with increasing temperature. The contents of phenols, aldehydes, and alcohols in bio-oil produced from the shell were higher than those in bio-oil derived from rice straw.
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•High-energy electron beam irradiation (HE-EBI) significantly enhanced the antioxidant activity of ovalbumin (OVA).•The antioxidant activity of OVA was enhanced in a dose-dependent ...manner.•The mechanism of HE-EBI on enhancing the antioxidant activity in OVA was investigated.•HE-EBI treatment unfolded the OVA to “honeycomb” structure.•HE-EBI-stimulated oxidation exposed the high-antioxidant activity peptides.
The effects of high-energy electron beam irradiation (HE-EBI) at various doses (0, 25, 50, 75, and 100 kGy) on the antioxidant activity of ovalbumin (OVA) were studied, and the molecular mechanism was investigated. The results showed that the antioxidant activity of HE-EBI-treated OVA was significantly enhanced in a dose-dependent manner. The irradiated OVA structure gradually unfolded to form a “honeycomb” structure, exposing the buried hydrophobic and free sulfhydryl groups inside the molecule. Two oxidation sites (M35 and T170), adjacent to the antioxidant peptide were identified by mass spectrometry, possibly exposing the antioxidant peptide through structural deconvolution. In addition, aspartic residues generated dicarbonyl compound under high-energy electron beam stress, and its accumulation further enhanced the antioxidant activity. Conclusively, HE-EBI can enhance the antioxidant activity of OVA through ionization effects, providing valuable information for the potential application of HE-EBI in the food industry.
Purple red rice bran (PRRBA), a by-product of the rice polishing process, is frequently thrown away, resulting in a waste of resources. This study investigated the effects of PRRBA on the pasting, ...rheological property, chemical structure, microstructure, and water migration of rice starch. The results demonstrated that the peak viscosity (PV), final viscosity (FV), and activation energy (retrogradation energy) of rice starch were all decreased by a dose of PRRBA. Furthermore, the gel strength and hardness of rice starch were positively correlated with the addition of PRRBA. Rice starchs particle size distribution can be improved by PRRBA, which may be a result of the non-covalent bonds that exist between PRRBA and rice starch. The addition of PRRBA resulted in a decrease in the spin relaxation time (T2) of rice starch, from 259.7 to 143.6 ms. This can be attributed to that PRRBA improved the water-holding capacity of rice starch. These results could contribute to the development of high-value-added products of PRRBA and facilitate the application of anthocyanins in starch-based foods.
•The low dose of PRRBA reduced the viscosity of starch, while the high dose showed a contrary effect.•The gel strength and hardness of rice starch were enhanced by adding PRRBA.•PRRBA increased starch particle size of rice starch by non-covalent bonds.•PRRBA improved the water-holding capacity of rice starch gel.
This study explored the effect of diverse coagulants (glucono-δ-lactone (GDL), gypsum (GYP), microbial transglutaminase (MTGase), and white vinegar (WVG)) on microstructure, quality, and digestion ...properties of tofu. The four kinds of tofu were significantly different in their structure, composition, and digestibility. Tofu coagulated with MTGase had the highest springiness and cohesiveness while GDL tofu had the highest enthalpy (6.54 J/g). However, the WVG and GYP groups outperformed others in terms of thermodynamic, and digestion properties. The WVG group exhibited the highest nitrogen release (84.3%), water content, denaturation temperature, and the highest free-SH content but the lowest S-S content. Compared to WVG, the GYP group had the highest ash content, hardness, and chewiness. Results demonstrated that the tofu prepared by WVG and GYP show high digestibility. Meanwhile, the former has better thermal properties and the latter has better texture properties.
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•Tofu coagulated with GYP and WVG exhibited higher digestibility than others.•The WVG group showed the highest thermal stability, digestibility, and water content.•Compared with WVG,the GYP tofu had the highest ash content, hardness, and chewiness•Tofu coagulated with MTGase had the highest springiness and cohesiveness.
